We analysed 16 populations of Dactylorhiza majalis subsp. majalis from northern Poland, simultaneously utilizing both morphological and molecular data. Genetic differentiation was examined using five microsatellite loci, and morphological variation was assessed for 23 characters. At the species level, our results showed a moderate level of genetic diversity (A = 6.00; Ae = 1.86; Ho = 0.387; FIS = 0.139) which varied between the studied populations (A = 2.60–4.20; Ae = 1.68–2.39; Ho = 0.270–0.523; FIS = ?0.064–0.355). A significant excess of homozygotes was detected in five population, while excess of heterozygotes was observed in four populations, but the latter values were statistically insignificant. Moderate, but clear between population genetic differentiation was found (FST = 0.101; p < 0.001). Considering pairwise‐FST and number of migrants among populations, we recognized three population groups (I, II, III), where the first could be further divided into two subgroups (Ia, Ib). These three groups differed with respect to gene flow values (Nm = 0.39–1.12). The highest number of migrants per generation was noticed among populations of subgroup Ia (8.58), indicative of a central panmictic population with free gene flow surrounded by peripatric local populations (Ib) with more limited gene flow. Geographic isolation, habitat fragmentation and limited seed dispersal are inferred to have caused limitations to gene flow among the three indicated population groups. There was a significant correlation between the morphological and genetic distance matrices. A weak but significant pattern of isolation by distance was also observed (r = 0.351; p < 0.05). 相似文献
The physicochemical variations of soil, such as temperature, pH, nutrients, and the type of plant cultivation, affect the diversity of cyanobacteria, whether heterocystous or not. The aim of this study was to identify the species of cyanobacteria in a soil and the effect of environmental characteristics on cyanobacteria. Soil samples collected from six different agricultural sites in Al Diwaniyah city/Iraq during September 2016 in the autumn season were analyzed, and the physicochemical characteristics of the samples were measured using approved methods.
The results showed significant correlation and differences between cyanobacteria composition, distribution, and physicochemical factors among soil sites. The Agricultural soil was slightly alkaline and moderately saline and contained abundant nutrients, cations and a high percentage of organic matter. All these characteristics influenced the distribution and diversity of cyanobacteria. Ninety-six species were identified, including four heterocystous species represented by Anabaena, Calothrix, Cylnidrospermum, and Nostoc. However, the non-heterocystous were represented by 13 species: Aphanocapsa, Aphanothece, Arthrospira, Chroococcus, Gloeocapsa, Lyngbya, Merismopedia, Microcystis, Microcoleus, Oscillatoria, Phormidium, Schizothrix, and Spirulina. The dominant species of cyanobacteria was Oscillatoria, followed by Phormidium, Chroococcus, Gleocapsa and Lyngbya. The highest value of Shannon’s and Simpson’s diversities were registered in the Ghammas site, which is a paddy field, but the lowest was registered in the Afak site, cultivated with the alfalfa plant. Soil was classified as finely textured with silty clayey characterization, favorable for cyanobacteria growth. 相似文献
In this study, the denitrification performance of the mixotrophic biological reactor was investigated under varying Fe(II)/Mn(II) molar ratio conditions. Results indicate that the optimal nitrate removal ratio occurred at an Fe(II)/Mn(II) molar ratio of 9:1, pH of 7, with an HRT of 10?h. When the reactor was performing under optimal conditions, the nitrate removal reached 100.00% at a rate of 0.116?mmol·L?1·h?1. The proportion of oxidized Fe(II) and Mn(II) reached 99.29% and 21.88%, respectively. High-throughput sequencing results show that Pseudomonas was the dominant species in the mixotrophic biological reactor. Furthermore, the relative abundance of Pseudomonas and denitrification performance was significantly influenced by variation in the Fe(II)/Mn(II) molar ratio. 相似文献
The Stegosauria represents an iconic group of ornithischian dinosaurs, with a fossil record spanning the Middle Jurassic to the Late Cretaceous. In this contribution I present the first detailed analysis of the relationship between disparity and diversity through the evolutionary history of the group. The analysis has been performed on a recently published cladistic dataset, allowing the separate study of the signals deriving from discrete characters and from continuous morphometric characters. Whereas the disparity as sum of variance is decoupled with respect to diversity, the sum of ranges provides a signal fairly consistent with the trend in the number of taxa. Both sub-data sets show that evolution of stegosaurs can be considered essentially as symmetrical, i.e. the maximum exploration of the possible morphospace takes place about half way through the history of the group, with subsequent significant decline until extinction in the Upper Cretaceous. An interesting result is a decoupling of the tempo and mode of evolution of the cranium and postcranium in stegosaurs. Specifically, the evolutionary radiation with maximum saturation of morphospace is anticipated in the cranial skeleton, with maximum peak in the Oxfordian; in contrast, the postcranium explores the largest number of morphotypes subsequently during the Kimmeridgian. 相似文献
We studied patterns of phylogenetic and compositional diversity of fleas parasitic on small mammals and asked whether these patterns are affected by environmental variation or evolutionary/historical processes. We considered environmental variation via both off‐host (air temperature, precipitation, the amount of green vegetation, latitude) and host‐associated (phylogenetic and species composition) environments. The indicators of evolutionary/historical processes were phylogenetic and compositional uniqueness estimated via phylogenetic or compositional, respectively, β‐diversity of either fleas or hosts. We found that phylogenetic uniqueness of flea assemblages was the main predictor of their phylogenetic diversity in all realms. In addition, host phylogenetic diversity and uniqueness played also some role in the Palearctic, whereas the effect of the off‐host environment was either extremely weak or absent. Compositional diversity of fleas was consistently affected by compositional diversity of hosts in all realms except the Neotropics. The effect of the off‐host environment on compositional flea diversity was substantial in all realms except the Palearctic. No effect of latitude on either metric of flea diversity was found. We conclude that phylogenetic diversity of fleas is driven mainly by evolutionary/historical processes, whereas drivers of their compositional diversity are associated with current ecological conditions. 相似文献
Forest fragmentation and defaunation are considered the main drivers of biodiversity loss, yet the synergistic effects of landscape changes and biotic interactions on assemblage structure have been poorly investigated. Here, we use an extensive dataset of 283 assemblages and 105 species of small mammals to understand how defaunation of medium and large mammals and forest fragmentation change the community composition and diversity of rodents and marsupials in tropical forests of South America. We used structured equation models to investigate the relationship between small mammal species, functional and phylogenetic diversity with forest size, forest cover and the occurrence of medium and large mammals. The best‐fit model showed that defaunation reduced functional diversity, and that species diversity of small mammals increased with forest patch size. Forest cover did not affect functional and phylogenetic diversity. Our results indicate that occurrence of medium and large sized mammals (probably acting as predators, or competitors of small mammals) and forest patch size help to retain species and functional diversity in small mammal communities. Further, the number of species in a small mammal community was critical to the maintenance of phylogenetic diversity, and may have a pronounced influence on the ecological functions played by small mammals. Identifying how phylogenetic and functional diversity change in function of human pressures allows us to better understand the contribution of extant lineages to ecosystem functioning in tropical forests. 相似文献